sudoers(4) MAINTENANCE COMMANDS sudoers(4)
NNNNAAAAMMMMEEEE
sudoers - list of which users may execute what
DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
The _s_u_d_o_e_r_s file is composed of two types of entries:
aliases (basically variables) and user specifications
(which specify who may run what). The grammar of _s_u_d_o_e_r_s
will be described below in Extended Backus-Naur Form
(EBNF). Don't despair if you don't know what EBNF is; it
is fairly simple, and the definitions below are annotated.
QQQQuuuuiiiicccckkkk gggguuuuiiiiddddeeee ttttoooo EEEEBBBBNNNNFFFF
EBNF is a concise and exact way of describing the grammar
of a language. Each EBNF definition is made up of _p_r_o_d_u_c_­
_t_i_o_n _r_u_l_e_s. E.g.,
symbol ::= definition | alternate1 | alternate2 ...
Each _p_r_o_d_u_c_t_i_o_n _r_u_l_e references others and thus makes up a
grammar for the language. EBNF also contains the follow­
ing operators, which many readers will recognize from reg­
ular expressions. Do not, however, confuse them with
"wildcard" characters, which have different meanings.
? Means that the preceding symbol (or group of sym­
bols) is optional. That is, it may appear once or
not at all.
* Means that the preceding symbol (or group of sym­
bols) may appear zero or more times.
+ Means that the preceding symbol (or group of sym­
bols) may appear one or more times.
Parentheses may be used to group symbols together. For
clarity, we will use single quotes ('') to designate what
is a verbatim character string (as opposed to a symbol
name).
AAAAlllliiiiaaaasssseeeessss
There are four kinds of aliases: User_Alias, Runas_Alias,
Host_Alias and Cmnd_Alias.
Alias ::= 'User_Alias' User_Alias (':' User_Alias)* |
'Runas_Alias' Runas_Alias (':' Runas_Alias)* |
'Host_Alias' Host_Alias (':' Host_Alias)* |
'Cmnd_Alias' Cmnd_Alias (':' Cmnd_Alias)*
User_Alias ::= NAME '=' User_List
Runas_Alias ::= NAME '=' Runas_List
January 16, 2002 1.6.5 1
sudoers(4) MAINTENANCE COMMANDS sudoers(4)
Host_Alias ::= NAME '=' Host_List
Cmnd_Alias ::= NAME '=' Cmnd_List
NAME ::= [A-Z]([A-Z][0-9]_)*
Each _a_l_i_a_s definition is of the form
Alias_Type NAME = item1, item2, ...
where _A_l_i_a_s___T_y_p_e is one of User_Alias, Runas_Alias,
Host_Alias, or Cmnd_Alias. A NAME is a string of upper­
case letters, numbers, and the underscore characters
('_'). A NAME mmmmuuuusssstttt start with an uppercase letter. It is
possible to put several alias definitions of the same type
on a single line, joined by a colon (':'). E.g.,
Alias_Type NAME = item1, item2, item3 : NAME = item4, item5
The definitions of what constitutes a valid _a_l_i_a_s member
follow.
User_List ::= User |
User ',' User_List
User ::= '!'* username |
'!'* '%'group |
'!'* '+'netgroup |
'!'* User_Alias
A User_List is made up of one or more usernames, uids
(prefixed with '#'), System groups (prefixed with '%'),
netgroups (prefixed with '+') and other aliases. Each
list item may be prefixed with one or more '!' operators.
An odd number of '!' operators negate the value of the
item; an even number just cancel each other out.
Runas_List ::= Runas_User |
Runas_User ',' Runas_List
Runas_User ::= '!'* username |
'!'* '#'uid |
'!'* '%'group |
'!'* +netgroup |
'!'* Runas_Alias
A Runas_List is similar to a User_List except that it can
also contain uids (prefixed with '#') and instead of
User_Aliases it can contain Runas_Aliases.
Host_List ::= Host |
Host ',' Host_List
January 16, 2002 1.6.5 2
sudoers(4) MAINTENANCE COMMANDS sudoers(4)
Host ::= '!'* hostname |
'!'* ip_addr |
'!'* network(/netmask)? |
'!'* '+'netgroup |
'!'* Host_Alias
A Host_List is made up of one or more hostnames, IP
addresses, network numbers, netgroups (prefixed with '+')
and other aliases. Again, the value of an item may be
negated with the '!' operator. If you do not specify a
netmask with a network number, the netmask of the host's
ethernet _i_n_t_e_r_f_a_c_e(s) will be used when matching. The
netmask may be specified either in dotted quad notation
(e.g. 255.255.255.0) or CIDR notation (number of bits,
e.g. 24). A hostname may include shell-style wildcards
(see `Wildcards' section below), but unless the hostname
command on your machine returns the fully qualified host­
name, you'll need to use the _f_q_d_n option for wildcards to
be useful.
Cmnd_List ::= Cmnd |
Cmnd ',' Cmnd_List
commandname ::= filename |
filename args |
filename '""'
Cmnd ::= '!'* commandname |
'!'* directory |
'!'* Cmnd_Alias
A Cmnd_List is a list of one or more commandnames, direc­
tories, and other aliases. A commandname is a fully qual­
ified filename which may include shell-style wildcards
(see `Wildcards' section below). A simple filename allows
the user to run the command with any arguments he/she
wishes. However, you may also specify command line argu­
ments (including wildcards). Alternately, you can specify
"" to indicate that the command may only be run wwwwiiiitttthhhhoooouuuutttt
command line arguments. A directory is a fully qualified
pathname ending in a '/'. When you specify a directory in
a Cmnd_List, the user will be able to run any file within
that directory (but not in any subdirectories therein).
If a Cmnd has associated command line arguments, then the
arguments in the Cmnd must match exactly those given by
the user on the command line (or match the wildcards if
there are any). Note that the following characters must
be escaped with a '\' if they are used in command argu­
ments: ',', ':', '=', '\'.
January 16, 2002 1.6.5 3
sudoers(4) MAINTENANCE COMMANDS sudoers(4)
DDDDeeeeffffaaaauuuullllttttssss
Certain configuration options may be changed from their
default values at runtime via one or more Default_Entry
lines. These may affect all users on any host, all users
on a specific host, or just a specific user. When multi­
ple entries match, they are applied in order. Where there
are conflicting values, the last value on a matching line
takes effect.
Default_Type ::= 'Defaults' ||
'Defaults' ':' User ||
'Defaults' '@' Host
Default_Entry ::= Default_Type Parameter_List
Parameter ::= Parameter '=' Value ||
Parameter '+=' Value ||
Parameter '-=' Value ||
'!'* Parameter ||
Parameters may be ffffllllaaaaggggssss, iiiinnnntttteeeeggggeeeerrrr values, ssssttttrrrriiiinnnnggggssss, or
lllliiiissssttttssss. Flags are implicitly boolean and can be turned off
via the '!' operator. Some integer, string and list
parameters may also be used in a boolean context to dis­
able them. Values may be enclosed in double quotes (")
when they contain multiple words. Special characters may
be escaped with a backslash (\).
Lists have two additional assignment operators, += and -=.
These operators are used to add to and delete from a list
respectively. It is not an error to use the -= operator
to remove an element that does not exist in a list.
Note that since the _s_u_d_o_e_r_s file is parsed in order the
best place to put the Defaults section is after the Host,
User, and Cmnd aliases but before the user specifications.
FFFFllllaaaaggggssss:
long_otp_prompt
When validating with a One Time Password
scheme (SSSS////KKKKeeeeyyyy or OOOOPPPPIIIIEEEE), a two-line prompt is
used to make it easier to cut and paste the
challenge to a local window. It's not as
pretty as the default but some people find it
more convenient. This flag is _o_f_f by default.
ignore_dot If set, ssssuuuuddddoooo will ignore '.' or '' (current
dir) in the PATH environment variable; the
PATH itself is not modified. This flag is _o_f_f
by default.
January 16, 2002 1.6.5 4
sudoers(4) MAINTENANCE COMMANDS sudoers(4)
mail_always Send mail to the _m_a_i_l_t_o user every time a
users runs ssssuuuuddddoooo. This flag is _o_f_f by default.
mail_badpass
Send mail to the _m_a_i_l_t_o user if the user run­
ning sudo does not enter the correct password.
This flag is _o_f_f by default.
mail_no_user
If set, mail will be sent to the _m_a_i_l_t_o user
if the invoking user is not in the _s_u_d_o_e_r_s
file. This flag is _o_n by default.
mail_no_host
If set, mail will be sent to the _m_a_i_l_t_o user
if the invoking user exists in the _s_u_d_o_e_r_s
file, but is not allowed to run commands on
the current host. This flag is _o_f_f by
default.
mail_no_perms
If set, mail will be sent to the _m_a_i_l_t_o user
if the invoking user allowed to use ssssuuuuddddoooo but
the command they are trying is not listed in
their _s_u_d_o_e_r_s file entry. This flag is _o_f_f by
default.
tty_tickets If set, users must authenticate on a per-tty
basis. Normally, ssssuuuuddddoooo uses a directory in the
ticket dir with the same name as the user run­
ning it. With this flag enabled, ssssuuuuddddoooo will
use a file named for the tty the user is
logged in on in that directory. This flag is
_o_f_f by default.
lecture If set, a user will receive a short lecture
the first time he/she runs ssssuuuuddddoooo. This flag is
_o_n by default.
authenticate
If set, users must authenticate themselves via
a password (or other means of authentication)
before they may run commands. This default
may be overridden via the PASSWD and NOPASSWD
tags. This flag is _o_n by default.
root_sudo If set, root is allowed to run ssssuuuuddddoooo too. Dis­
abling this prevents users from "chaining"
ssssuuuuddddoooo commands to get a root shell by doing
something like "sudo sudo /bin/sh". This flag
is _o_n by default.
log_host If set, the hostname will be logged in the
(non-syslog) ssssuuuuddddoooo log file. This flag is _o_f_f
January 16, 2002 1.6.5 5
sudoers(4) MAINTENANCE COMMANDS sudoers(4)
by default.
log_year If set, the four-digit year will be logged in
the (non-syslog) ssssuuuuddddoooo log file. This flag is
_o_f_f by default.
shell_noargs
If set and ssssuuuuddddoooo is invoked with no arguments
it acts as if the ----ssss flag had been given.
That is, it runs a shell as root (the shell is
determined by the SHELL environment variable
if it is set, falling back on the shell listed
in the invoking user's /etc/passwd entry if
not). This flag is _o_f_f by default.
set_home If set and ssssuuuuddddoooo is invoked with the ----ssss flag
the HOME environment variable will be set to
the home directory of the target user (which
is root unless the ----uuuu option is used). This
effectively makes the ----ssss flag imply ----HHHH. This
flag is _o_f_f by default.
always_set_home
If set, ssssuuuuddddoooo will set the HOME environment
variable to the home directory of the target
user (which is root unless the ----uuuu option is
used). This effectively means that the ----HHHH
flag is always implied. This flag is _o_f_f by
default.
path_info Normally, ssssuuuuddddoooo will tell the user when a com­
mand could not be found in their PATH environ­
ment variable. Some sites may wish to disable
this as it could be used to gather information
on the location of executables that the normal
user does not have access to. The disadvan­
tage is that if the executable is simply not
in the user's PATH, ssssuuuuddddoooo will tell the user
that they are not allowed to run it, which can
be confusing. This flag is _o_f_f by default.
preserve_groups
By default ssssuuuuddddoooo will initialize the group vec­
tor to the list of groups the target user is
in. When _p_r_e_s_e_r_v_e___g_r_o_u_p_s is set, the user's
existing group vector is left unaltered. The
real and effective group IDs, however, are
still set to match the target user. This flag
is _o_f_f by default.
fqdn Set this flag if you want to put fully quali­
fied hostnames in the _s_u_d_o_e_r_s file. I.e.:
instead of myhost you would use myhost.mydo­
main.edu. You may still use the short form if
January 16, 2002 1.6.5 6
sudoers(4) MAINTENANCE COMMANDS sudoers(4)
you wish (and even mix the two). Beware that
turning on _f_q_d_n requires ssssuuuuddddoooo to make DNS
lookups which may make ssssuuuuddddoooo unusable if DNS
stops working (for example if the machine is
not plugged into the network). Also note that
you must use the host's official name as DNS
knows it. That is, you may not use a host
alias (CNAME entry) due to performance issues
and the fact that there is no way to get all
aliases from DNS. If your machine's hostname
(as returned by the hostname command) is
already fully qualified you shouldn't need to
set _f_q_d_n. This flag is _o_f_f by default.
insults If set, ssssuuuuddddoooo will insult users when they enter
an incorrect password. This flag is _o_f_f by
default.
requiretty If set, ssssuuuuddddoooo will only run when the user is
logged in to a real tty. This will disallow
things like "rsh somehost sudo ls" since
_r_s_h(1) does not allocate a tty. Because it is
not possible to turn of echo when there is no
tty present, some sites may with to set this
flag to prevent a user from entering a visible
password. This flag is _o_f_f by default.
env_editor If set, vvvviiiissssuuuuddddoooo will use the value of the EDI­
TOR or VISUAL environment variables before
falling back on the default editor list. Note
that this may create a security hole as it
allows the user to run any arbitrary command
as root without logging. A safer alternative
is to place a colon-separated list of editors
in the editor variable. vvvviiiissssuuuuddddoooo will then only
use the EDITOR or VISUAL if they match a value
specified in editor. This flag is off by
default.
rootpw If set, ssssuuuuddddoooo will prompt for the root password
instead of the password of the invoking user.
This flag is _o_f_f by default.
runaspw If set, ssssuuuuddddoooo will prompt for the password of
the user defined by the _r_u_n_a_s___d_e_f_a_u_l_t option
(defaults to root) instead of the password of
the invoking user. This flag is _o_f_f by
default.
targetpw If set, ssssuuuuddddoooo will prompt for the password of
the user specified by the ----uuuu flag (defaults to
root) instead of the password of the invoking
user. This flag is _o_f_f by default.
January 16, 2002 1.6.5 7
sudoers(4) MAINTENANCE COMMANDS sudoers(4)
set_logname Normally, ssssuuuuddddoooo will set the LOGNAME and USER
environment variables to the name of the tar­
get user (usually root unless the ----uuuu flag is
given). However, since some programs (includ­
ing the RCS revision control system) use LOG­
NAME to determine the real identity of the
user, it may be desirable to change this
behavior. This can be done by negating the
set_logname option.
stay_setuid Normally, when ssssuuuuddddoooo executes a command the
real and effective UIDs are set to the target
user (root by default). This option changes
that behavior such that the real UID is left
as the invoking user's UID. In other words,
this makes ssssuuuuddddoooo act as a setuid wrapper. This
can be useful on systems that disable some
potentially dangerous functionality when a
program is run setuid. Note, however, that
this means that sudo will run with the real
uid of the invoking user which may allow that
user to kill ssssuuuuddddoooo before it can log a failure,
depending on how your OS defines the interac­
tion between signals and setuid processes.
env_reset If set, ssssuuuuddddoooo will reset the environment to
only contain the following variables: HOME,
LOGNAME, PATH, SHELL, TERM, and USER (in addi­
tion to the SUDO_* variables). Of these, only
TERM is copied unaltered from the old environ­
ment. The other variables are set to default
values (possibly modified by the value of the
_s_e_t___l_o_g_n_a_m_e option). If ssssuuuuddddoooo was compiled
with the SECURE_PATH option, its value will be
used for the PATH environment variable. Other
variables may be preserved with the _e_n_v___k_e_e_p
option.
use_loginclass
If set, ssssuuuuddddoooo will apply the defaults specified
for the target user's login class if one
exists. Only available if ssssuuuuddddoooo is configured
with the --with-logincap option. This flag is
_o_f_f by default.
IIIInnnntttteeeeggggeeeerrrrssss:
passwd_tries
The number of tries a user gets to enter
his/her password before ssssuuuuddddoooo logs the failure
and exits. The default is 3.
IIIInnnntttteeeeggggeeeerrrrssss tttthhhhaaaatttt ccccaaaannnn bbbbeeee uuuusssseeeedddd iiiinnnn aaaa bbbboooooooolllleeeeaaaannnn ccccoooonnnntttteeeexxxxtttt:
January 16, 2002 1.6.5 8
sudoers(4) MAINTENANCE COMMANDS sudoers(4)
loglinelen Number of characters per line for the file
log. This value is used to decide when to
wrap lines for nicer log files. This has no
effect on the syslog log file, only the file
log. The default is 80 (use 0 or negate the
option to disable word wrap).
timestamp_timeout
Number of minutes that can elapse before ssssuuuuddddoooo
will ask for a passwd again. The default is
5. Set this to 0 to always prompt for a pass­
word. If set to a value less than 0 the
user's timestamp will never expire. This can
be used to allow users to create or delete
their own timestamps via sudo -v and sudo -k
respectively.
passwd_timeout
Number of minutes before the ssssuuuuddddoooo password
prompt times out. The default is 5, set this
to 0 for no password timeout.
umask Umask to use when running the command. Negate
this option or set it to 0777 to preserve the
user's umask. The default is 0022.
SSSSttttrrrriiiinnnnggggssss:
mailsub Subject of the mail sent to the _m_a_i_l_t_o user.
The escape %h will expand to the hostname of
the machine. Default is *** SECURITY informa­
tion for %h ***.
badpass_message
Message that is displayed if a user enters an
incorrect password. The default is Sorry, try
again. unless insults are enabled.
timestampdir
The directory in which ssssuuuuddddoooo stores its times­
tamp files. The default is _/_v_a_r_/_r_u_n_/_s_u_d_o.
passprompt The default prompt to use when asking for a
password; can be overridden via the ----pppp option
or the SUDO_PROMPT environment variable. Sup­
ports two escapes: "%u" expands to the user's
login name and "%h" expands to the local host­
name. The default value is Password:.
runas_default
The default user to run commands as if the ----uuuu
flag is not specified on the command line.
This defaults to root.
January 16, 2002 1.6.5 9
sudoers(4) MAINTENANCE COMMANDS sudoers(4)
syslog_goodpri
Syslog priority to use when user authenticates
successfully. Defaults to notice.
syslog_badpri
Syslog priority to use when user authenticates
unsuccessfully. Defaults to alert.
editor A colon (':') separated list of editors
allowed to be used with vvvviiiissssuuuuddddoooo. vvvviiiissssuuuuddddoooo will
choose the editor that matches the user's USER
environment variable if possible, or the first
editor in the list that exists and is exe­
cutable. The default is the path to vi on
your system.
SSSSttttrrrriiiinnnnggggssss tttthhhhaaaatttt ccccaaaannnn bbbbeeee uuuusssseeeedddd iiiinnnn aaaa bbbboooooooolllleeeeaaaannnn ccccoooonnnntttteeeexxxxtttt:
logfile Path to the ssssuuuuddddoooo log file (not the syslog log
file). Setting a path turns on logging to a
file; negating this option turns it off.
syslog Syslog facility if syslog is being used for
logging (negate to disable syslog logging).
Defaults to local2.
mailerpath Path to mail program used to send warning
mail. Defaults to the path to sendmail found
at configure time.
mailerflags Flags to use when invoking mailer. Defaults to
----tttt.
mailto Address to send warning and error mail to.
The address should be enclosed in double
quotes (") to protect against sudo interpret­
ing the @ sign. Defaults to root.
exempt_group
Users in this group are exempt from password
and PATH requirements. This is not set by
default.
verifypw This option controls when a password will be
required when a user runs ssssuuuuddddoooo with the ----vvvv
flag. It has the following possible values:
all All the user's _s_u_d_o_e_r_s entries for the
current host must have the NOPASSWD
flag set to avoid entering a password.
any At least one of the user's _s_u_d_o_e_r_s
entries for the current host must have
the NOPASSWD flag set to avoid
January 16, 2002 1.6.5 10
sudoers(4) MAINTENANCE COMMANDS sudoers(4)
entering a password.
never The user need never enter a password
to use the ----vvvv flag.
always The user must always enter a password
to use the ----vvvv flag.
The default value is `all'.
listpw This option controls when a password will be
required when a user runs ssssuuuuddddoooo with the ----llll.
It has the following possible values:
all All the user's _s_u_d_o_e_r_s entries for the
current host must have the NOPASSWD
flag set to avoid entering a password.
any At least one of the user's _s_u_d_o_e_r_s
entries for the current host must have
the NOPASSWD flag set to avoid enter­
ing a password.
never The user need never enter a password
to use the ----llll flag.
always The user must always enter a password
to use the ----llll flag.
The default value is `any'.
LLLLiiiissssttttssss tttthhhhaaaatttt ccccaaaannnn bbbbeeee uuuusssseeeedddd iiiinnnn aaaa bbbboooooooolllleeeeaaaannnn ccccoooonnnntttteeeexxxxtttt:
env_check Environment variables to be removed from the
user's environment if the variable's value
contains % or / characters. This can be used
to guard against printf-style format vulnera­
bilties in poorly-written programs. The argu­
ment may be a double-quoted, space-separated
list or a single value without double-quotes.
The list can be replaced, added to, deleted
from, or disabled by using the =, +=, -=, and
! operators respectively. The default list of
environment variable to check is printed when
ssssuuuuddddoooo is run by root with the _-_V option.
env_delete Environment variables to be removed from the
user's environment. The argument may be a
double-quoted, space-separated list or a sin­
gle value without double-quotes. The list can
be replaced, added to, deleted from, or dis­
abled by using the =, +=, -=, and ! operators
respectively. The default list of environment
variable to remove is printed when ssssuuuuddddoooo is run
January 16, 2002 1.6.5 11
sudoers(4) MAINTENANCE COMMANDS sudoers(4)
by root with the _-_V option.
env_keep Environment variables to be preserved in the
user's environment when the _e_n_v___r_e_s_e_t option
is in effect. This allows fine-grained con­
trol over the environment ssssuuuuddddoooo-spawned pro­
cesses will receive. The argument may be a
double-quoted, space-separated list or a sin­
gle value without double-quotes. The list can
be replaced, added to, deleted from, or dis­
abled by using the =, +=, -=, and ! operators
respectively. This list has no default mem­
bers.
When logging via _s_y_s_l_o_g(3), ssssuuuuddddoooo accepts the following
values for the syslog facility (the value of the ssssyyyysssslllloooogggg
Parameter): aaaauuuutttthhhhpppprrrriiiivvvv (if your OS supports it), aaaauuuutttthhhh, ddddaaaaeeee­­­­
mmmmoooonnnn, uuuusssseeeerrrr, llllooooccccaaaallll0000, llllooooccccaaaallll1111, llllooooccccaaaallll2222, llllooooccccaaaallll3333, llllooooccccaaaallll4444, llllooooccccaaaallll5555,
llllooooccccaaaallll6666, and llllooooccccaaaallll7777. The following syslog priorities are
supported: aaaalllleeeerrrrtttt, ccccrrrriiiitttt, ddddeeeebbbbuuuugggg, eeeemmmmeeeerrrrgggg, eeeerrrrrrrr, iiiinnnnffffoooo, nnnnoooottttiiiicccceeee,
and wwwwaaaarrrrnnnniiiinnnngggg.
UUUUsssseeeerrrr SSSSppppeeeecccciiiiffffiiiiccccaaaattttiiiioooonnnn
User_Spec ::= User_list Host_List '=' Cmnd_Spec_List \
(':' User_Spec)*
Cmnd_Spec_List ::= Cmnd_Spec |
Cmnd_Spec ',' Cmnd_Spec_List
Cmnd_Spec ::= Runas_Spec? ('NOPASSWD:' | 'PASSWD:')? Cmnd
Runas_Spec ::= '(' Runas_List ')'
A uuuusssseeeerrrr ssssppppeeeecccciiiiffffiiiiccccaaaattttiiiioooonnnn determines which commands a user may
run (and as what user) on specified hosts. By default,
commands are run as rrrrooooooootttt, but this can be changed on a
per-command basis.
Let's break that down into its constituent parts:
RRRRuuuunnnnaaaassss____SSSSppppeeeecccc
A Runas_Spec is simply a Runas_List (as defined above)
enclosed in a set of parentheses. If you do not specify a
Runas_Spec in the user specification, a default Runas_Spec
of rrrrooooooootttt will be used. A Runas_Spec sets the default for
commands that follow it. What this means is that for the
entry:
dgb boulder = (operator) /bin/ls, /bin/kill, /usr/bin/who
The user ddddggggbbbb may run _/_b_i_n_/_l_s, _/_b_i_n_/_k_i_l_l, and _/_u_s_r_/_b_i_n_/_l_p_r_m
-- but only as ooooppppeeeerrrraaaattttoooorrrr. E.g.,
January 16, 2002 1.6.5 12
sudoers(4) MAINTENANCE COMMANDS sudoers(4)
sudo -u operator /bin/ls.
It is also possible to override a Runas_Spec later on in
an entry. If we modify the entry like so:
dgb boulder = (operator) /bin/ls, (root) /bin/kill, /usr/bin/lprm
Then user ddddggggbbbb is now allowed to run _/_b_i_n_/_l_s as ooooppppeeeerrrraaaattttoooorrrr,
but _/_b_i_n_/_k_i_l_l and _/_u_s_r_/_b_i_n_/_l_p_r_m as rrrrooooooootttt.
NNNNOOOOPPPPAAAASSSSSSSSWWWWDDDD aaaannnndddd PPPPAAAASSSSSSSSWWWWDDDD
By default, ssssuuuuddddoooo requires that a user authenticate him or
herself before running a command. This behavior can be
modified via the NOPASSWD tag. Like a Runas_Spec, the
NOPASSWD tag sets a default for the commands that follow
it in the Cmnd_Spec_List. Conversely, the PASSWD tag can
be used to reverse things. For example:
ray rushmore = NOPASSWD: /bin/kill, /bin/ls, /usr/bin/lprm
would allow the user rrrraaaayyyy to run _/_b_i_n_/_k_i_l_l, _/_b_i_n_/_l_s, and
_/_u_s_r_/_b_i_n_/_l_p_r_m as root on the machine rushmore as rrrrooooooootttt
without authenticating himself. If we only want rrrraaaayyyy to be
able to run _/_b_i_n_/_k_i_l_l without a password the entry would
be:
ray rushmore = NOPASSWD: /bin/kill, PASSWD: /bin/ls, /usr/bin/lprm
Note, however, that the PASSWD tag has no effect on users
who are in the group specified by the exempt_group option.
By default, if the NOPASSWD tag is applied to any of the
entries for a user on the current host, he or she will be
able to run sudo -l without a password. Additionally, a
user may only run sudo -v without a password if the
NOPASSWD tag is present for all a user's entries that per­
tain to the current host. This behavior may be overridden
via the verifypw and listpw options.
WWWWiiiillllddddccccaaaarrrrddddssss ((((aaaakkkkaaaa mmmmeeeettttaaaa cccchhhhaaaarrrraaaacccctttteeeerrrrssss))))::::
ssssuuuuddddoooo allows shell-style _w_i_l_d_c_a_r_d_s to be used in pathnames
as well as command line arguments in the _s_u_d_o_e_r_s file.
Wildcard matching is done via the PPPPOOOOSSSSIIIIXXXX fnmatch(3) rou­
tine. Note that these are _n_o_t regular expressions.
* Matches any set of zero or more characters.
? Matches any single character.
[...] Matches any character in the specified range.
January 16, 2002 1.6.5 13
sudoers(4) MAINTENANCE COMMANDS sudoers(4)
[!...] Matches any character nnnnooootttt in the specified range.
\x For any character "x", evaluates to "x". This is
used to escape special characters such as: "*",
"?", "[", and "}".
Note that a forward slash ('/') will nnnnooootttt be matched by
wildcards used in the pathname. When matching the command
line arguments, however, as slash ddddooooeeeessss get matched by
wildcards. This is to make a path like:
/usr/bin/*
match /usr/bin/who but not /usr/bin/X11/xterm.
EEEExxxxcccceeeeppppttttiiiioooonnnnssss ttttoooo wwwwiiiillllddddccccaaaarrrrdddd rrrruuuulllleeeessss::::
The following exceptions apply to the above rules:
"""" If the empty string "" is the only command line
argument in the _s_u_d_o_e_r_s entry it means that com­
mand is not allowed to be run with aaaannnnyyyy arguments.
OOOOtttthhhheeeerrrr ssssppppeeeecccciiiiaaaallll cccchhhhaaaarrrraaaacccctttteeeerrrrssss aaaannnndddd rrrreeeesssseeeerrrrvvvveeeedddd wwwwoooorrrrddddssss::::
The pound sign ('#') is used to indicate a comment (unless
it occurs in the context of a user name and is followed by
one or more digits, in which case it is treated as a uid).
Both the comment character and any text after it, up to
the end of the line, are ignored.
The reserved word AAAALLLLLLLL is a built in _a_l_i_a_s that always
causes a match to succeed. It can be used wherever one
might otherwise use a Cmnd_Alias, User_Alias, Runas_Alias,
or Host_Alias. You should not try to define your own
_a_l_i_a_s called AAAALLLLLLLL as the built in alias will be used in
preference to your own. Please note that using AAAALLLLLLLL can be
dangerous since in a command context, it allows the user
to run aaaannnnyyyy command on the system.
An exclamation point ('!') can be used as a logical _n_o_t
operator both in an _a_l_i_a_s and in front of a Cmnd. This
allows one to exclude certain values. Note, however, that
using a ! in conjunction with the built in ALL alias to
allow a user to run "all but a few" commands rarely works
as intended (see SECURITY NOTES below).
Long lines can be continued with a backslash ('\') as the
last character on the line.
Whitespace between elements in a list as well as special
syntactic characters in a _U_s_e_r _S_p_e_c_i_f_i_c_a_t_i_o_n ('=', ':',
'(', ')') is optional.
January 16, 2002 1.6.5 14
sudoers(4) MAINTENANCE COMMANDS sudoers(4)
The following characters must be escaped with a backslash
('\') when used as part of a word (e.g. a username or
hostname): '@', '!', '=', ':', ',', '(', ')', '\'.
EEEEXXXXAAAAMMMMPPPPLLLLEEEESSSS
Below are example _s_u_d_o_e_r_s entries. Admittedly, some of
these are a bit contrived. First, we define our _a_l_i_a_s_e_s:
# User alias specification
User_Alias FULLTIMERS = millert, mikef, dowdy
User_Alias PARTTIMERS = bostley, jwfox, crawl
User_Alias WEBMASTERS = will, wendy, wim
# Runas alias specification
Runas_Alias OP = root, operator
Runas_Alias DB = oracle, sybase
# Host alias specification
Host_Alias SPARC = bigtime, eclipse, moet, anchor :\
SGI = grolsch, dandelion, black :\
ALPHA = widget, thalamus, foobar :\
HPPA = boa, nag, python
Host_Alias CUNETS = 128.138.0.0/255.255.0.0
Host_Alias CSNETS = 128.138.243.0, 128.138.204.0/24, 128.138.242.0
Host_Alias SERVERS = master, mail, www, ns
Host_Alias CDROM = orion, perseus, hercules
# Cmnd alias specification
Cmnd_Alias DUMPS = /usr/bin/mt, /usr/sbin/dump, /usr/sbin/rdump,\
/usr/sbin/restore, /usr/sbin/rrestore
Cmnd_Alias KILL = /usr/bin/kill
Cmnd_Alias PRINTING = /usr/sbin/lpc, /usr/bin/lprm
Cmnd_Alias SHUTDOWN = /usr/sbin/shutdown
Cmnd_Alias HALT = /usr/sbin/halt, /usr/sbin/fasthalt
Cmnd_Alias REBOOT = /usr/sbin/reboot, /usr/sbin/fastboot
Cmnd_Alias SHELLS = /usr/bin/sh, /usr/bin/csh, /usr/bin/ksh, \
/usr/local/bin/tcsh, /usr/bin/rsh, \
/usr/local/bin/zsh
Cmnd_Alias SU = /usr/bin/su
Here we override some of the compiled in default values.
We want ssssuuuuddddoooo to log via _s_y_s_l_o_g(3) using the _a_u_t_h facility
in all cases. We don't want to subject the full time
staff to the ssssuuuuddddoooo lecture, and user mmmmiiiilllllllleeeerrrrtttt need not give
a password. In addition, on the machines in the _S_E_R_V_E_R_S
Host_Alias, we keep an additional local log file and make
sure we log the year in each log line since the log
entries will be kept around for several years.
# Override built in defaults
Defaults syslog=auth
Defaults:FULLTIMERS !lecture
Defaults:millert !authenticate
Defaults@SERVERS log_year, logfile=/var/log/sudo.log
January 16, 2002 1.6.5 15
sudoers(4) MAINTENANCE COMMANDS sudoers(4)
The _U_s_e_r _s_p_e_c_i_f_i_c_a_t_i_o_n is the part that actually deter­
mines who may run what.
root ALL = (ALL) ALL
%wheel ALL = (ALL) ALL
We let rrrrooooooootttt and any user in group wwwwhhhheeeeeeeellll run any command on
any host as any user.
FULLTIMERS ALL = NOPASSWD: ALL
Full time sysadmins (mmmmiiiilllllllleeeerrrrtttt, mmmmiiiikkkkeeeeffff, and ddddoooowwwwddddyyyy) may run
any command on any host without authenticating themselves.
PARTTIMERS ALL = ALL
Part time sysadmins (bbbboooossssttttlllleeeeyyyy, jjjjwwwwffffooooxxxx, and ccccrrrraaaawwwwllll) may run
any command on any host but they must authenticate them­
selves first (since the entry lacks the NOPASSWD tag).
jack CSNETS = ALL
The user jjjjaaaacccckkkk may run any command on the machines in the
_C_S_N_E_T_S alias (the networks 128.138.243.0, 128.138.204.0,
and 128.138.242.0). Of those networks, only 128.138.204.0
has an explicit netmask (in CIDR notation) indicating it
is a class C network. For the other networks in _C_S_N_E_T_S,
the local machine's netmask will be used during matching.
lisa CUNETS = ALL
The user lllliiiissssaaaa may run any command on any host in the
_C_U_N_E_T_S alias (the class B network 128.138.0.0).
operator ALL = DUMPS, KILL, PRINTING, SHUTDOWN, HALT, REBOOT,\
/usr/oper/bin/
The ooooppppeeeerrrraaaattttoooorrrr user may run commands limited to simple main­
tenance. Here, those are commands related to backups,
killing processes, the printing system, shutting down the
system, and any commands in the directory _/_u_s_r_/_o_p_e_r_/_b_i_n_/.
joe ALL = /usr/bin/su operator
The user jjjjooooeeee may only _s_u(1) to operator.
pete HPPA = /usr/bin/passwd [A-z]*, !/usr/bin/passwd root
The user ppppeeeetttteeee is allowed to change anyone's password
except for root on the _H_P_P_A machines. Note that this
assumes _p_a_s_s_w_d(1) does not take multiple usernames on the
command line.
bob SPARC = (OP) ALL : SGI = (OP) ALL
January 16, 2002 1.6.5 16
sudoers(4) MAINTENANCE COMMANDS sudoers(4)
The user bbbboooobbbb may run anything on the _S_P_A_R_C and _S_G_I
machines as any user listed in the _O_P Runas_Alias (rrrrooooooootttt
and ooooppppeeeerrrraaaattttoooorrrr).
jim +biglab = ALL
The user jjjjiiiimmmm may run any command on machines in the _b_i_g_l_a_b
netgroup. SSSSuuuuddddoooo knows that "biglab" is a netgroup due to
the '+' prefix.
+secretaries ALL = PRINTING, /usr/bin/adduser, /usr/bin/rmuser
Users in the sssseeeeccccrrrreeeettttaaaarrrriiiieeeessss netgroup need to help manage the
printers as well as add and remove users, so they are
allowed to run those commands on all machines.
fred ALL = (DB) NOPASSWD: ALL
The user ffffrrrreeeedddd can run commands as any user in the _D_B
Runas_Alias (oooorrrraaaacccclllleeee or ssssyyyybbbbaaaasssseeee) without giving a password.
john ALPHA = /usr/bin/su [!-]*, !/usr/bin/su *root*
On the _A_L_P_H_A machines, user jjjjoooohhhhnnnn may su to anyone except
root but he is not allowed to give _s_u(1) any flags.
jen ALL, !SERVERS = ALL
The user jjjjeeeennnn may run any command on any machine except for
those in the _S_E_R_V_E_R_S Host_Alias (master, mail, www and
ns).
jill SERVERS = /usr/bin/, !SU, !SHELLS
For any machine in the _S_E_R_V_E_R_S Host_Alias, jjjjiiiillllllll may run
any commands in the directory /usr/bin/ except for those
commands belonging to the _S_U and _S_H_E_L_L_S Cmnd_Aliases.
steve CSNETS = (operator) /usr/local/op_commands/
The user sssstttteeeevvvveeee may run any command in the directory
/usr/local/op_commands/ but only as user operator.
matt valkyrie = KILL
On his personal workstation, valkyrie, mmmmaaaatttttttt needs to be
able to kill hung processes.
WEBMASTERS www = (www) ALL, (root) /usr/bin/su www
On the host www, any user in the _W_E_B_M_A_S_T_E_R_S User_Alias
(will, wendy, and wim), may run any command as user www
(which owns the web pages) or simply _s_u(1) to www.
January 16, 2002 1.6.5 17
sudoers(4) MAINTENANCE COMMANDS sudoers(4)
ALL CDROM = NOPASSWD: /sbin/umount /CDROM,\
/sbin/mount -o nosuid\,nodev /dev/cd0a /CDROM
Any user may mount or unmount a CD-ROM on the machines in
the CDROM Host_Alias (orion, perseus, hercules) without
entering a password. This is a bit tedious for users to
type, so it is a prime candidate for encapsulating in a
shell script.
SSSSEEEECCCCUUUURRRRIIIITTTTYYYY NNNNOOOOTTTTEEEESSSS
It is generally not effective to "subtract" commands from
ALL using the '!' operator. A user can trivially circum­
vent this by copying the desired command to a different
name and then executing that. For example:
bill ALL = ALL, !SU, !SHELLS
Doesn't really prevent bbbbiiiillllllll from running the commands
listed in _S_U or _S_H_E_L_L_S since he can simply copy those com­
mands to a different name, or use a shell escape from an
editor or other program. Therefore, these kind of
restrictions should be considered advisory at best (and
reinforced by policy).
CCCCAAAAVVVVEEEEAAAATTTTSSSS
The _s_u_d_o_e_r_s file should aaaallllwwwwaaaayyyyssss be edited by the vvvviiiissssuuuuddddoooo
command which locks the file and does grammatical check­
ing. It is imperative that _s_u_d_o_e_r_s be free of syntax
errors since ssssuuuuddddoooo will not run with a syntactically incor­
rect _s_u_d_o_e_r_s file.
When using netgroups of machines (as opposed to users), if
you store fully qualified hostnames in the netgroup (as is
usually the case), you either need to have the machine's
hostname be fully qualified as returned by the hostname
command or use the _f_q_d_n option in _s_u_d_o_e_r_s.
FFFFIIIILLLLEEEESSSS
/etc/sudoers List of who can run what
/etc/group Local groups file
/etc/netgroup List of network groups
SSSSEEEEEEEE AAAALLLLSSSSOOOO
_r_s_h(1), _s_u_d_o(1m), _v_i_s_u_d_o(8), _s_u(1), _f_n_m_a_t_c_h(3).
January 16, 2002 1.6.5 18